Timing device



June 11, 1946.

H. J. DlBBLEE TIMING DEVICE Filed April 21, 1944 INVENTOR.

HAROLD J. DIBBLEE I BY %@M.

ATTORNEY Patented June 11, 1946 UNITED STATES PATENT OFFICE 2,401,747TIMING DEVICE Harold J. Dibblee, Newtown, Pa. Application April 21,1944, Serial No. 532,200

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 13 Claims.

The invention described herein may be manufactured and used by or forthe- Government for governmental purposes, without the payment to me ofany royalty thereon.

My present invention relates to timing devices, and more particularly,to devices of the general character indicated for determining the timeelapsing between the occurrence of two successive events, especially,but not necessarily, two events so related to each other that thehappening of the second is dependent upon and initiated by the happeningof the first.

While not limited thereto, my present invention is eminently suitablefor measuring the time intervening the energization of the operatingcoil of an electro-magnetic relay and the opening or closing of thecontacts thereof; or, the de-energization of the coil of said relay andthe opening or closing of the contact thereof.

Devices in the prior art, designed for similar purposes, have certaindisadvantages attendant thereto. For example, the limit of accuracy ofsome of such devices is of the order of plus or minus 0.01 second, andthe design of some of such devices is such that their use i limited torelays in which the functioning of the contacts is brought about only bythe energization of the coil, and not by the de-energization thereof.Other prior art devices require high-speed clock mechanisms actuated byquick-acting clutches which introduce errors preventing accuratemeasurements. Still other devices utilize sensitive electricoscillographs, which are delicate and not particularly suitable forroutine laboratory technique. All of these devices are elaborate,cumbersome, and costly.

It is, therefore, the main object of my present invention to eliminatethe foregoing disadvantages by providing a relatively simple andinexpensive time-measuringdevice which is extremely accurate, down to amicrosecond.

It is a further object of my present invention to provide atime-measuring device which is completely electronic in operation, andtherefore includes no elements which, because of inertia, ordinarilytend to introduceerrors.

It is a still further object of my present invention generally toimprove the art of measuring short time intervals, and provide a methodand means therefor which is capable of a wide variety of applications. I

These, and other objects and advantages, which will become apparent asthe detailed description progresses, are attained in the presentinvention in the following manner:

'2 It is known that the voltage on acapacitor, which is being dischargedthrough a resistor, may be determined from the equation:

where E1=the voltage to which the capacitori initially charged,

Ez=the voltage remaining across the capacitor at the end of thedischarge period,

t =the discharge time in seconds,

R=the value in ohms of the resistor through which the capacitor is beingdischarged,

and

C =the'capacitance in farads of the capacitor being discharged.

Therefore, if a capacitor is charged to a known voltage, then dischargedfor an unknown period of time, and the residual voltage across saidcalog, El -log, E

pacitor is determined, the length of time during which current flowedthrough said capacitor may readily be calculated. I

The present'invention makes use of this fact by causing a capacitor,which has been charged to a known voltage, to commence discharging,through a resistor and a vacuum tuba-upon the happening of the first ofthe above mentioned successive events, the vacuum tube functioning as acontrol valve which becomes instantaneously cut off upon the happeningof the second of said events. By measuring the potential across saidcapacitor at said cutofi, and utilizing the principles involved in theabove equation, the drop in the potential across said capacitor,occasioned by said discharge, maybe translated intothe time elapsingbetween the happening of said two events. The initial and finalmeasurements of the voltage across the capacitor are preferably madewith a modified. vacuum-tube voltmeter so as not to draw any currentfrom the circuit. The initial measurement of the voltage acrossthecapacitor in the exercise of the'present invention is indicatedherein by the voltmeter needle. at its. maximum reading. The finalmeasurement of the voltage acrossthe capacitor is indicated herein by aredline or a red mark at 37% of the full scale on the voltmeter, asdetermined mathematically by the above equation and as referred to withmore particularity hereinafter. The red line is of use during thecalibration Of the device.

In the accompanying specification shall describe, and in the annexeddrawing show, what is at present considered a preferred embodiment Asmentioned previously, the acid to olefin monomer ratio is an importantfactor in securing the desired polymerization reaction. Since animportant object o! my invention is to secure not only a polymerizationreaction, but to also recover the two types of product, i. e., thesaturated hydrocarbons and the highly unsaturated, terpenelike productssoluble in the catalyst, the relative proportions of acid to totalhydrocarbons in the reaction zone is important. In the absence oi inertsolvents an amount of acid of from about 20% up to about 400% by weightor the olefinic hydrocarbons may be utilized, or expressed in anotherway from 25% to 500% by weight of olefins may be added to thehydrofluoric acid with separation possible into readily separablelayers. Preferably the amount of olefins added is from 33%% to 200% byweight. Where inert solvents are utilized, the amount of olefin whichmay be added to the acid-hydrocarbon mixture will largely depend uponthe relative proportion of acid and inert hydrocarbon solvent, and isnormally within the range of from 16%% up to about 200% by weight of theamount of acid, with amounts from 25% to 150% by weight preferred. Thediilerence in preferred ranges is due to the fact that the inert solventdoes not react to produce larger molecules (which as a result ofhydrogen exchange distribute themselves between the acid and hydrocarbonphases) but remains as a distinct hydrocarbon phase. Hence, assumingthat the amount of solvent is at least as great as the amount of acid,the minimum amount of olefins necessarily added, where solvents areemployed, is generally reduced by about one-half to obtain satisiactoryconditions of layer separation. similarly, especially where it isdesirable to use relatively large amounts oi inert solvent, the maximumamount oi olefin which may be added to the catalyst with satisfactoryseparation after the reaction has been completed, is reduced.

The process may be carried out, in either the presence or absence ofsolvents. under conditions similar to those utilized in carrying out.alkylation reactions, or the conditions used are what might be termed"alkylation conditions" with respect to pressure, temperature (withinthe ranges indicated), reaction system, mode of introduction ofreactants and the like.

Since the reaction gives oi! a substantial amount heat, it is usuallydesirable to provide suitable cooling means in order to maintain thetemperature within the preferred limits. Usually the reaction will becarried out so that the hydrogen fluoride catalyst is in liquid phase,and, therefore, in such cases sumcient pressure should be provided tomaintain the catalyst in liquid phase. However, such procedure requiresonly sufilcient ressure to maintain the inert solvent, it any, and thehydrogen fluoride in the liquid state. The olefin is then passed throughthe well-agitated liquid at such a rate that it all reacts tohigherbolling hydrocarbons, wherefore no rise in pressure results.Accordingly, relatively low pressures can be used.

Since, in addition to the initial olefin polymerization, I desire toallow hydrogen exchange reactions to occur within the original polymerproducts, further contacting or the reaction mixture with the acidcatalyst is desirable. The amount of residence time, o! the hydrocarbonproducts in contact with the catalyst, required to achieve substantialor nearly complete saturation of the acid immiscible hydrocarbons varieswith the reaction conditions and the particular olefin monomer beingprocessed. At normal room temperature levels, total residence times offrom 30 minutes to three hours are generally satisfactory, althoughthese residence time are not intended as limiting on the operation of myprocess. The residence time is correlatable with the reactiontemperature and the degree of saturation of the hydrocarbon layerproducts desired.

Referring to the drawing one possible form of carrying out the processof my invention is diagrammatically illustrated, which enables thecontinuous production of the conjunct polymer products. According to theform illustrated, the reaction is carried out in the presence of anormal paraihn hydrocarbon solvent.

To an emulsion of hydrofluoric acid and an inert solvent such as normalbutane, obtained in the manner hereinafter described, in a coil I intemperature control zone 2, an olefin is introduced through line 3provided with a suitable pump I. The contact time of the olefin chargewith the acid catalyst should be sufficiently long within thetemperature control zone 2 so that a substantial portion of the olefinreacts therein to form the olefin dimers, trimers, etc. From coil I, theolefin polymer, solvent-catalyst mixture is led through lines 5 and I toreactor 8 provided with a suitable agitator 5, wherein the emulsion ismaintained for the desired residence time to permit the polymerizationreactions to become completed and allow hydrogen exchange to occurbetween the olefin polymers as previously described. Product mixture iscontinuously withdrawn from the reactor 8, and sent through line ID tosettling tank I5 wherein the emulsion is allowed to stratify into anupper hydrocarbon phase and a lower acid catalyst phase. From the lowerportion of the settling tank, catalyst phase is continuously withdrawnthrough line I6, and sent to fractionator I'l, wherein the major portionof the hydrofluoric acid is distilled off from the highly unsaturatedterpene-like polymers contained therein. The hydrofluoric acid vaporsoverhead from fractionator II are then sent through line I8 to condenserI9, collected in receiver 20, and returned through lines 2|, 22 and 23to reaction coil I. Line 23 is provided with a suitable pump 24 toprovide the necessary acid circulation. Make-up hydrofluoric acid isadmitted, as necessary, to line 22 through line 25, provided with a.control valve 26. The highly unsaturated polymer is removed from thebottom of the fractionator I7, and sent through line 30, provided with asuitable pump 3I, to acid stripper 32. In acid stripper 32, the finaltraces of hydrofiuoric acid are removed from the unsaturated polymerproduct by scrubbing the polymer with a hot inert gas such as nitrogenor methane introduced through line 33. This includes not onlyhydrofluoric acid present as such, but also hydrogen fluoride which mayhave added to double bonds in the unsaturated polymer and is driven offby moderate heating. The overhead from the stripper 32 is sent tocondenser 34 through line 35, and any condensable material, principallyhydrofluoric acid, collected in receiver 38, provided with a suitablevent 31, and recovered from line 38. Any hydrogen fluoride escaping withthe vent gases may be recovered by any suitable means. The unsaturatedpolymer product is recovered from the bottom of the acid stripperthrough line 39.

The hydrocarbon phase is withdrawn from the top of settling tank I5, andsent through line 45 to solvent stripper 46. Solvent vapors are takencontacts 38-3l or 32-33. The switch 21 is then closed to engage thecontact 28. This places the selected capacitor across the potentialexisting between ground and some point tn the potentiometer l8, which isnegative with respect to ground, to charge said capacitor to saidpotential.

The switch 21 is then thrown upwardly to engage the contact 28, therebyconnecting the previously grounded side of the selected capacitor to thegride of tube 2 Up to this time the tube 2| will have been blocked sinceits grid, being isolated, will have collected a negative charge due toelectrons emitted from its cathode.

The left hand plate of the selected capacitor is below ground potentialsince the tap l8 of the potentiometer I8 is below the ground potentialof the tap IT on the potentiometer IS. The cathode of the tube 2| isgrounded thru the small impedance of the milliarnmeter 22. Theconnection of the grid of the tube to the previously grounded side ofthe selected capacitor by the changing of the switch arm 28 from thecontact 28 to the contact 28 causes the tube 2| to begin to conductsince its grid and cathode are initially at ground potential and theplate thereof has a positive potential. The tube 2| will continue toconduct at a constant rate which causes meter 22 to read a constantvalue which preferably is adjusted to the maximum full-scale mark on themeter. This condition pertains until the beginning of the interval to betimed at which instant the selected capacitor begins to discharge thruits R.-C. network thereby reducing the potential on the grid of tube 2|.The tube 2| will continue to conduct at a decreasing rate as indicatedby the movement of the needle downwardly on the scale of the meter 22 asthe selected capacitor continues to discharge. At the termination of theinterval to be timed the selected capacitor ceases to discharge therebyholding the grid of tube 2| at the residual potential of the capacitorand causing the meter 22 to indicate a constant reading. The scale beingcalibrated in time units, this final meter reading indicates the elapsedtime.

The tube 2|, when so conducting is operating preferably on the straightportion of its characteristic curve and hence for a given plate voltage,the plate current will vary linearly with variations in grid potential.With a given grid potential the plate current of the tube 2| will varyin an approximately linear relation with variations in plate potential.The plate potential of the tube 2| is determined by the setting of thetap on the variable resistor 28.

With the grid of the tube 2| connected to the previously grounded-sideoi the selected capacitor, the resistor 28 is adjusted so that the tubedraws suflicient plateicurrent to give a full scale needle deflection onthe meter 22. During the time of the making of this adjustment, the tube2| is drawing current from thebleeder or potentiometer l6 because of thebias on the tube 2| as controlled by the charged selected capacitor. Thevacuum tube voltmeter 22 is thereby adjusted to its initial positionwith the needle reading thereof at a maximum value.

The selected capacitor is discharged thru the tube 88 beginning with thethrowing of the switch 36 upwardly. The tube 88 controls the time ofdischarge of the selected condenser. The grid bias on the tube 88 iscontrolled by the opening or the closing of the relay contacts 14 and'15.

The interval of time between the upwardly closing of the switch 38 andthe opening or closing of the relay contacts 14 and 15 determines thechange in position of the needle of the meter 22. The change in positionof the needle of the meter 22 is determined by the R.-C. time of theselected capacitor 34 or 35 and a selected resistor 1'|--85, inclusive,from the switch 18. The meter 22 may, if preferred, be disposed inseries between the potentiometer tap I6 and the late of the tube 2|.When the meter 22 is so positioned in the circuit the cathode terminalsof the tube 2| are connected to ground.

The procedure to be followed from this point on depends upon the type ofrelay being tested;

that is, whether the relay is one in which the ergization of the relaycoil, or one in which the contacts are normally closed, and open upondeenergization of the relay coil, or, finally, one in which the contactsare normally open, and close upon de-energization of the relay coil.

The four procedures will be described in the order mentioned.

In the first case, the switch 31 is closed in its lower position, andthe'switch 38 is closed in its upper position. The switches 36 and 38remain open.

The relay to be tested has its coil conniected, in series with anappropriate source of D. C., such as a battery 86 or the like, to thebinding posts H and 12, and the normally closed con cts of said relayare connected across the bin ing posts 14 and I5. It will be noted thatthe grid of the tube 88 is connected directly to the oathode of saidtube through the resistor 88, contacts 62, 58,6l, and 66 of the switch38, the relay contacts connected to the-binding posts 14 and I5, and thecontacts 65 and 68 of said switch 38.

Upon the application of plate voltage to the tube 88, upon closing theswitch 38 upwardly the tube 88 will become conducting so as to permitthe selected capacitor to discharge therethrough. For this purpose, theadjustable arm 81 of the selector switch 16 is engaged with anappropriate one of the resistors ll-85, inclusive, the switch 36 beingclosed. The latter operation initiates two simultaneous events. Closingof the circuit between the contacts 4| and 43, the switch 31 beingclosed downwardly energizes the relay coil connected to-the bindingposts "II and 12 by way of the contacts 52-5|l and 535| of the switch81. At the same time, engagement of the contacts 48 and 42 connects theplate of the tube 88 to the positive side of the selected capacitorthrough the chosen resistor of the selector switch 16, therebypermitting said selected capacitor to commence to discharge.Energization of the relay coil, after the passage of a certain time,causes the relay contacts to open, and break the circuit at the bindingposts 14 and 15. This removes the direct connection between the grid andcathode of the tube 88, and causes said grid immediately to assume apotential which is negative with respect to said cathode, therebyblocking the tube 88, this condition being brought about through thebias battery 88, contacts 58 and 64 of the switch 38, resistor 13,contacts 58 and 62 of said switch 38, and resistor 88. This negativepotential blocks the tube 88 simultaneously with the opening of therelay contacts, and the charge remaining on the selected capacitor istherefore indicative of the time during which the R. C. circuit was inoperation since the motion of the pointer on the meter 22 is stopped atthe blocking of the tube It. The read ing on the meter 22 is anindication of the p tential remaining across the -capacitor, whichreading will. of course. be lower than the full scale reading to whichthe meter was set at the start of the test. Interpretation of thisreading in terms of time will be better understood after considerationbelow of the method of calibrating the device.

Assume now that the relay to be tested is one whose contacts arenormally closed, and open when the relay coil is energized. To carry outthis test. switches 31 and 33 are both closed in their down positions,and switches 38 and 30 are open. The operating coil and relay contactsare respectively connected, as before, to the binding posts Ii-l2 andll-Iii.

The selected capacitor 34 or 35 is charged by throwing the switch 21into engagement with the contact 23. said switch then being thrownupwardly into engagement with the contact 23, and

the resistor 20 being adjusted so that the tube- 2| of the vacuum tubevoltmeter draws sumcient current to obtain full scale deflection on themeter 22.

It will be noted that the grid of the tube 33 is connected throughresistor 30, contacts 62 and 31 of the switch 39, resistor 13, andcontacts 83 and 33 of said switch 33 to the cathode of said tube, and,upon the application of plate voltage to said tube. through one of theresistors of the selector switch ll, said tube will conduct. The switch33 is now closed. As in the preceding case, the relay coil is energizedand plate voltage is applied to the tube It so as to conduct the chargefrom the selected capacitor. when th relay contacts close, the grid ofthe tube 33 is immediately connected to the negative side of the biasbattery 33 through resistor 30, contacts 62, i1, 83, and 38 of theswitch 39, the relay contacts across the binding posts H and I3, and thecontacts 66 and ll of said switch 39. The tube 30 is thereforeimmediately biased below cutoff, and, as in the preceding test, areading of the meter 22 gives an indication of the elapsed time.

Assume now that the relay to be tested is one whose contacts arenormally closed, and open when the coil thereof is de-energized. The

. switches 31 and 39 are both thrown into their up positions, and theswitches 36 and 33 are both closed. It will be noted that the grid 01the tube 33 will then be biased to cutoff through the contacts 53 and Nof the switch 33. The tube 33, therefore, will not conduct even thoughthe plate thereof is connected to the charged capacitor through theswitch 36. The switch 33 is now opened, and this causes two simultaneousactions. The bias is removed from the tube Is, the grid of said tubebecoming connected to the cathode thereof through resistor 30, contacts32, 33, II, and 63 of the switch 33, the relay contacts connected acrossthe binding posts I4 and 15, and the contacts 83 and 80 of said switch33. This permits the tube 33 to conduct as long as the relay contactsremain closed. At the same time, the relay coil connected across thebindin posts II and 12 becomes de-energlzed by the opening of thecontacts 53 and 51 of the switch 33. Upon the opening of the relaycontacts, after the passage of time, the grid of the tube 33 againbecomes connected to the negative terminal of the bias battery 33, andsaid tube, as in the previous case, becomes cut off.

Finally, it is to be assumed that the relay to be tested is one whosecontacts are normally open,

and close when the coil thereof is de-energized. For this test theswitch 31 is closed in its up position, the switch 39 is closed in itsdown position, and th switches 38 and 33 are both closed. As in theimmediately preceding case, th tube II is biased below cutofl throushthe contacts I and 56 of the switch 33. When said switch 33 is opened,the relay coil is de-energized and, at the same time, the blocking biason the tube 33 is removed. The grid of said tube is therefore connectedto the cathode thereof, and said tube will conduct until the relaycontacts close, at which time, negative bias is again applied to thegrid of the tube and the latter becomes non-conducting.

It will be noted that the only difference between the various proceduresoutlined for the four types of tests is the switching sequence. Theobject in each case isto have the discharge tube 88 in a conductingstate only during the time interval to be measured. This is accomplishedby having th grid of said tube connected to the cathode at the beginningof this time interval, and biasing the tube below cutoil at the end ofthis time interval.

This completes the description of the operation and mode of use of thepresent invention and there remains, merely, a description of the mannerin which the devic is calibrated, this being as follows:

The calibration of this device depends upon the fact that th voltageacross a capacitor which is bein discharged through a resistor drops toa value in other words, 37% of its initial charge, when the dischargeperiod is equal to the time constant of the resistance-capacitancecombination. For calibration purposes, a resistor of megohms is used incombination with a 2 mid. capacitor, this combination having a timeconstant of one minute. Therefore, if the circuit is permitted todischarge for one minute, the voltage across the capacitor will drop toa value of 37% of its initial charge, and, due to the linearcharacteristic of the vacuum tube voltmeter being used, this willcorrespond to a scale reading approximately 37% of full scale. .Asdescribed, the device incorporates a timer 9i which, when thepush-button s2 is operated, automatically closes the circuit across thebinding posts I4 and 15 for a period of one minute.

In order, therefore, to calibrate the device, the switch 25 is closed inits down position to insert the 2 mid. capacitor into the circuit. Theswitch 21 is then engaged with the contact 23 to charge the capacitor tothe potential determined by the position of the adjustable arm 19 of thepotentiometer Ill. The selector switch 13 is then manipulated to bringinto the circuit the resistor having a value of 30 megohms. The switches31 and 39 are then thrown up, and the switches 36 and 33 remain open.The switch 21 is then thrown up to engage the contact 29, and thevariable resistor 20 is adjusted so as to obtain a full scale deflectionon the meter 22. The push button 82 is now depressed, causing the timer3| to short circuit the binding posts H and 15 for a period of oneminute by operation of an electrical clock or the like, that closes thecam switch 9! at the end of one minute from the start of the electriccapacitor 35 will have dropped to approximately 37% of its initialvalue. The scale of the meter 22 is marked, for example, with a red lineat the point indicated by the meter needle at this time. Now, knowingthe position on the scale of the meter 22 which corresponds to 37% ofthe initial voltage, said scale may be calibrated in terms of timeintermediate the 37% red mark and full scale deflection.

For subsequent use of the device, the needle of the meter 22 may bereadjusted to the red line on the scale thereof if necessary b thereadjustment of the potentiometer l8 and the rheostat 20 to assureaccuracy in the results thereof.

The meter 22 may be provided with additional conveniently calibratedscales by utilizing different time constants available by use of thedifferent resistors ll-85, inclusive, in the switch 16 and well knownresistance-capacitance mathematical computations.

This completes the description of the present invention.

It will be noted from all of the foregoing that I have provided arelatively simple and inexpensive time m asuring device which isextremely accurate since the full range of the meter 22 scale can beused with the smaller condenser and the smallest resistor, the meter,condenser, and resistors being of high degrees of accuracy, even down toa microsecond, by means of which the time elapsing between twosuccessive events, for example, the energization or de-energization ofthe operating coil of an electro-magnetic relay, and the functioning ofthe contacts of said relay, may be precisely determined.

It will further be noted that my present invention is substantiallyelectronic in operation and avoids the use of elements which, because ofinertia, ordinarily tend to introduce errors.

And it will further be noted that while I have described the presentinvention as particularly useful in testing the lags inherent inelectromagnetic relays, it is not necessarily limited to suchapplication, but may find a wide variety of other uses.

Other objects and advantages of my present invention will readily occurto those skilled in the art, to which the same relates.

I claim:

1. The method of utilizing an R.-C. network containing a capacitor andan electron discharge device for determining the time elapsing betweenthe occurrence of two successive events which includes the steps of:initially charging the capacitor of said network to a predeterminedreference value as indicated by a direct current vacuum voltmetercalibrated to read directly in units of time to provide a timemeterwhile maintaining said discharge device inoperative; rendering saiddischarge device operative upon the happening of the first of said twosuccessive events whereby said capacitor commences to dischargetherethrough of which events either event may be an opening of acontact; interrupting the operation of said discharge device, andconsequently the discharge of said capacitor, upon the happening of thesecond of said two successive events; determining the residual chargeremaining upon said capacitor; and reading the desired elapsed timebetween the occurrence of the events from the timemeter.

2. i'he method of utilizing an R.-C. network containing a capacitor andan electron discharge tube for determining the time elapsing between theoccurrence of two successive events which includes the steps ofinitially charging the capacitor of said network to a predeterminedreference value as indicated by a vacuum voltmeter reading directly intime units while maintaining said discharge tube nonconducting;rendering said discharge tube conducting upon the happening of the firstof said two successive events whereby said capacitor commences todischarge therethrough; rendering said discharge tube nonconducting uponthe happening of the second of said two successive events whereby thedischarge of said capacitor is interrupted by the closing of a contact;determining the residual charge remaining upon said capacitor; andtaking the reading of the elapsed time between the events directly fromthe voltmeter.

3. The method of utilizing an R.-C. network containing a capacitor andan electron discharge tube for determining the time elapsing between theoccurrence of two successive events which includes the steps ofinitially charging the capacitor of said network to a predeterminedreference value while maintaining said discharge tube without any platevoltage applied thereto; applying plate vol a e to said discharge tubeupon the happening of the first of said two successive events wherebysaid capacitor commences to discharge therethrough; biasing saiddischarge tube below cutoff upon the happening of the second of said twosuccessive events whereby the discharge of said capacitor isinterrupted; opposing the discharging of the capacitor by placing itscharge in opposition to the original voltage thereon; determining theresidual charge remaining upon saidcapacitor; and translating thedifference between said initial and residual charges includes the stepsof initially charging the capacitor of said network to a predeterminedreference value while maintaining said discharge tube biased belowcutofl; lifting the bias on said discharge tube so as to render the sameconducting upon the happening of the first of said two successive eventswhereby said capacitor commences to discharge therethrcugh atsubstantially an exponential rate and opposed by its original voltagechange; applying bias to said discharge tube sufficient to render thesame-nonconducting upon the happening of the second of said twosuccessive events whereby the discharge of said capacitor isinterrupted; determining the residual charge remaining upon saidcapacitor; and translating the difference between said initial andresidual charges into terms of time.

5; Means for determining the time elapsing between the occurrence of twosuccessive eventscomprising: an R.-C. network containing 9. capacitor;means for initially charging the capacitor of said network to apredetermined reference value; an electron discharge device; means forso connecting said network and said. discharge device as to permit saidcapacitor tc commence discharging against the voltage of its originalcharge upon the happening of the first Jf said two suc cessive events;means for controlling the operation of said discharge device whereby thedischarge of said capacitor is interrupted upon the happening of thesecond of said two successive events; and means for measuring theresidual charge remaining upon said capacitor, and translating thedifference between said initial and residual charges into terms 01'time.

6. Means for determining the time elapsing between the occurrence of twosuccessive events comprising: an R.-C. network containing a capacitor asa part thereoi; means for initially charging the capacitor of saidnetwork to a predetermined rei'erence value; an electron discharge tube;means for so connecting said network and said discharge tube as topermit said capacitor to commence discharging against the voltage of itsoriginal charge through said tube upon the happening oi the first saidtwo successive events; means for biasing said discharge tube beyondcutoi! upon the happening 0! the second of said two successive eventswhereby the discharge of said capacitor is interrupted; and means formeasuring the residual charge remainl upon said capacitor, andtranslating the dii'- ierence between said initial and residual chargesinto terms of time.

7. Means for determining the time elapsing between the occurrence of twosuccessive events comprising: an R.-C. network containing a capacitor;means for initially charging the capacitor 0! said network to apredetermined relerence value; an electron discharge tube; means for soconnecting said network and said discharge tube as to apply the chargeacquired by said capacitor as plate voltage to said discharge tubewhereby said capacitor commences to discharge therethrough against thevoltage at its original charge upon the happening 0! the first of saidtwo successive events; means for biasing said discharge tube beyondcutofl upon the happening of the second of said two successive eventswhereby the discharge or said capacitor is interrupted; and means formeasuring the residual charge remaining upon said capacitor, andtranslating the dill'erence between said initial and residual chargesinto terms of time.

8. Means for determining the time elapsing between the occurrence of twosuccessive events comprising: an R.-C. network containing a capacitor;means'ior initially charging the capacitor of said network to apredetermined reference value; an electron discharge tube; means formaintaining said discharge tube normally biased beyond cutoii; means forso connecting said network and said discharge tube as to lift said biasand render said tube conducting upon the happening oi the first 01' saidtwo successive events whereby said capacitor is permitted to dischargetherethrough against the voltage of its original charge; means forrestoring said cutoi! bias to said discharge tube upon the happening 0!the second of said two successive events whereby the discharge of saidcapacitor is interrupted; and means tor measuring the residual chargeremaining upon said capacitor, and translating the diflerence betweensaid initial and residual charges into terms of time.

9. A timer, comprising in combination a capacitor, a direct currentvacuum tube voltmeter for measuring a charge on said capacitor, avoltmeter needle sweeping across a scale part oi! the voltmeter, meansior adjusting a desired scale reading range oi the voltmeter needleindicating the magnitude of charge on said capacitor, a resistance inseries with said capacitor, a tube for controlling the time interval ofthe discharge 0! said capacitor, and means for controlling the grid biason said tube so that the tube will conduct or block as desired.

10. A timer, comprising in combination a chargeable capacitor, means forcharging said capacitor, an R.-C. circuit controlling the discharge rateof said capacitor, means ior initiating the discharge intervalimmediately upon the opening oi a contact apart from said R.-C. circuit,and means for terminating the interval immediately upon the opening of asecond contact apart from the R.-C. circuit.

11. A timer, comprising in combination a chargeable capacitor, means forcharging said capacitor, an R.-C. circuit controlling the discharge rateof said capacitor, means for initiating the discharge intervalimmediately upon the opening of a contact apart from R.-C. circuit, andmeans for terminating the interval immediately upon the closing of asecond contact apart from the R.-C. circuit.

12. A timer, comprising in combination a chargeable capacitor, means forcharging said capacitor, an R.-C. circuit controlling the discharge rateof said capacitor, means for initiating the discharge intervalimmediately upon the closing oi'a contact in said R.-C. circuit, andmeans for terminating the interval immediately upon the opening of asecond contact apart from the R.-C. circuit.

13. A timer, comprising in combination a capacitor, a resistor connectedto said capacitor in a circuit having a time constant, a voltmetermeasuring the potential across said capacitor and calibrated in time, afirst electronic tube having a control grid for initiating a dischargeoi said capacitor, a second electronic tube having a control grid forstopping a discharge of said capacitor, multiple ganged switching meansconnecting the circuit of said timer to the control circuit of a relaythrough the grid of said first electronic tube and adaptive to initiatedischarge 0! said capacitor immediately upon either make or break of thecontrol circuit, multiple ganged switching means connecting the circuitof said timer to a controlled circuit of the relay through the grid ofsaid second electronic tube and adaptive to stop discharge of saidcapacitor immediately upon either make or break of the controlledcircuit.

HAROLD J. DIBBLEE.

